二分图_KM模板

const int maxn = 55;
const int inf = 0x3f3f3f3f;

int n, m, ans, ans1, ans2;
int w[maxn][maxn], la[maxn], lb[maxn], match[maxn];
bool vis[maxn][maxn], va[maxn], vb[maxn];
int delta;

//匈牙利算法
inline bool find(int x) {
	va[x] = true;
	
	for(int y = 1; y <= m; y ++) {
		if(la[x] + lb[y] == w[x][y]) {
			if(!vb[y]) {
				vb[y] = true;
				if(!match[y] || find(match[y])) {
					match[y] = x;
					return true;
				}
			}
		}
	}
	
	return false;
}


//km
inline void KM(void) {

//初始化顶标
	for(int i = 1; i <= n; i ++) {
		la[i] = inf;
		
		for(int j = 1; j <= m; j ++) {
			lb[j] = 0;
			la[i] = max(la[i], w[i][j]);
		}
	}
	
	//初始化match
	memset(match, 0, sizeof match);
	ans2 = 0;
	
//为每个左边的点找到匹配
	for(int i = 1; i <= n; i ++) 
		while(true) {
			memset(va, false, sizeof va);
			memset(vb, false, sizeof vb);
			
			if(find(i)) break;
			
			delta = inf;
			for(int x = 1; x <= n; x ++)
			if(va[x])
			for(int y = 1; y <= m; y ++)
			if(!vb[y])
			delta = min(delta, la[x] + lb[y] - w[x][y]);
			
			for(int j = 1; j <= n; j ++)
			if(va[j]) la[j] -= delta;
			
			for(int j = 1; j <= m; j ++)
			if(vb[j]) lb[j] += delta;	
		} 
		
	for(int i = 1; i <= m; i ++) {
		int tmp = match[i];
		ans2 += w[tmp][i];
	}
}